import static org.junit.jupiter.api.Assertions.*;

class FactorialTest {

    @org.junit.jupiter.api.Test
    void factorial() {
        assertThrows(
                ArithmeticException.class,
                () -> Factorial.factorial(-3),
                "Cannot compute factorial of negative number."
        );
        assertThrows(
                ArithmeticException.class,
                () -> Factorial.factorial(-2),
                "Cannot compute factorial of negative number."
        );
        assertThrows(
                ArithmeticException.class,
                () -> Factorial.factorial(-1),
                "Cannot compute factorial of negative number."
        );
        assertEquals(1, Factorial.factorial(0));
        assertEquals(1, Factorial.factorial(1));
        assertEquals(2, Factorial.factorial(2));
        assertEquals(6, Factorial.factorial(3));
        assertEquals(24, Factorial.factorial(4));
        assertEquals(120, Factorial.factorial(5));
    }
}